JP2003329142A - Packing and sealing device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive packing and a sealing device wherein an oil film having a suitable thickness for preventing lack of the oil film between a seal lip and a member with which the seal lip slidably contacts. <P>SOLUTION: This packing 9A is provided with an annular base 17 and an annular seal lip 18 having a chevron cross section and projected inward on the inner circumference side of the base 17. The cylindrical clad part 19 made of the same material as the base 17 is integrally erected at an end part of the base 17, and the inner diameter of the clad part 19 is made larger than the inner diameter of the seal lip 18. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention seals a sliding gap formed between a reciprocating member such as a reciprocating piston rod and a supporting member such as a bearing for slidably guiding the reciprocating member. The present invention relates to a packing and a sealing device using the packing.

[0002]

2. Description of the Related Art Generally, in a gas spring, a hydraulic cylinder, a hydraulic shock absorber, and the like, a piston rod is reciprocally inserted in the cylinder through a piston, and the piston rod is slid at the opening end of the cylinder. A support member such as a bearing that guides movably is provided, and a seal device that constantly slides on the outer peripheral surface of the piston rod is provided to the support member, and a sliding gap formed between the support member and the piston rod is provided. The gas or hydraulic oil filled in the cylinder is prevented from leaking to the atmosphere side.

For example, a gas spring installed between a vehicle body and a back door in a vehicle such as an automobile is provided with a sealing device as shown in FIGS. 4 and 5, for example.

That is, a piston 2 is provided in a cylinder 1 having a bracket 11 at the tip thereof which is connected to the back door.
A piston rod 3 as a reciprocating member is reciprocally inserted through the piston 2, so that the piston 2 divides the inside of the cylinder 1 into a piston side chamber 4 and a rod side chamber 5, and these chambers 4 and 5 are separated from each other by the piston 2 They are communicated with each other through the orifice 6 formed in.

The piston rod 3 is reciprocally supported by a piston 2 as a support member provided at its end and a bearing 7 as a support member provided at the open end of the cylinder 1 so that the piston rod 3 can reciprocate. A packing 9 as a seal is provided on the inner end surface of 7 to form a sealing device.

The packing 9 is an outer peripheral lip 1 made of synthetic rubber and formed so as to project so as to contact the inner peripheral surface of the cylinder 1.
4, an inner peripheral lip 15 that is similarly formed so as to be in sliding contact with the outer peripheral surface of the piston rod 3, and these both lips 1
The metal cored bar 16 is integrally formed on the base end side of the metal wires 4, 15.

The inner peripheral lip 15 has a base portion 17 formed in an annular shape, and a seal having a mountain-shaped cross section formed on the inner peripheral side of the base portion 17 so as to project toward the outer peripheral surface of the piston rod as a facing surface thereof. The base 17 and the seal lip 18 are formed between the outer peripheral surface of the piston rod 3 and the inner peripheral surface of the bearing 7 by slidingly contacting the outer peripheral surface of the piston rod 3 in a state of being elastically deformed. By constantly sealing the sliding gap T, leakage of gas and hydraulic oil is prevented.

The outer peripheral lip 14 is brought into contact with the inner peripheral surface of the cylinder 1 in an elastically deformed state, seals a gap between the outer peripheral surface of the bearing 7 and the inner peripheral surface of the cylinder 1, and has a core metal. 16 is designed to support the load generated by the cylinder internal pressure.

Reference numeral 8 in the drawing denotes a retainer for preventing the piston 2 from directly contacting the packing 9.
Is a lubricating oil stored in the cylinder 1, and G is a high-pressure gas sealed in the cylinder 1.

Therefore, when the lock of the back door is released, the piston rod 3 expands due to the pressure receiving area difference between both end faces of the piston 2 due to the gas pressure sealed in the cylinder 1, and the back door is automatically opened. At the same time, the opening / closing speed is controlled by the flow resistance of the gas flowing through the orifice 6.

[0011]

In the gas spring constructed as described above, the lubricating oil O is supplied between the outer peripheral surface of the piston rod 3 and the inner peripheral lip 15, and a proper thickness is provided between them. By forming an oil film, friction is reduced and a predetermined sealing function is provided.

However, the above oil film thickness is a factor such as the viscosity of the lubricating oil, the operating speed of the gas spring, the maximum surface pressure gradient in the axial direction of the surface pressure generated between the inner peripheral lip 15 and the piston rod 3, and the like. For example, when the maximum surface pressure gradient has a large value, the oil film generally becomes thin.

That is, the surface pressure distribution by the conventional inner peripheral lip 15 is indicated by the characteristic Q of FIG. 3 due to the shape of the inner peripheral lip 15.

Further, in the case of the above gas spring,
Due to the enclosed high-pressure gas G, the cylinder internal pressure is 5 to 15
Since it is as high as about MPa, the surface pressure becomes high and the maximum surface pressure gradient R takes a large value, and the oil film is thinned as described above.

Therefore, it is conceivable that the oil film becomes too thin to cause oil film breakage, and the inner peripheral lip 15 corresponding to that part may be worn or damaged, thereby failing to achieve a predetermined sealing function.

Therefore, it has been conventionally proposed to form the tip of the seal lip 18 in an arc shape as a means for increasing the oil film, but the radius of this arc is as small as about 0.1 mm. However, there is a problem that the processing is difficult and the manufacturing cost is high.

An object of the present invention is to provide a packing which can always form an oil film of an appropriate thickness without causing oil film breakage between a seal lip and a member with which the seal lip is in sliding contact,
It is an inexpensive object to provide a sealing device using this packing.

[0018]

In order to achieve the above-mentioned object, one packing means of the present invention is an annular base portion and an annular seal having a mountain-shaped cross-section protruding inward toward the inner peripheral side of the base portion. In a packing having a lip, a tubular build-up portion made of the same material is integrally erected at the end of the base portion,
The inner diameter of the overlay portion is larger than the inner diameter of the seal lip.

In this case, the base portion, the seal lip, and the built-up portion constitute an inner peripheral lip, a core metal is provided at the base end of the base portion, and an outer peripheral lip radially opposed to the inner peripheral lip is provided on the core metal. May be.

Similarly, another packing means is a packing provided with an annular base portion and an annular seal lip having a mountain-shaped cross-section protruding outward on the outer peripheral side of the base portion. The same material is used for the end portion of the base portion. It is characterized in that the tubular build-up portion is made upright integrally and the outer diameter of the built-up portion is smaller than the outer diameter of the seal lip.

Similarly, one means of the sealing device is a packing that seals a sliding gap formed between a reciprocating member that reciprocates in the axial direction and a support member that slidably guides the reciprocating member. In a sealing device provided, an annular base portion holding the packing to a support member, an annular seal lip having a mountain cross-section protruding inward toward the inner peripheral side of the base portion and slidingly contacting the reciprocating member, and the base portion. A cylindrical build-up portion that is integrally erected at the end of the built-up material and has an inner diameter larger than the inner diameter of the seal lip, and has an annular shape between the reciprocating member. It is characterized in that a gap is formed.

Similarly, another means of the sealing device is a packing for sealing a sliding gap formed between a reciprocating member which reciprocates in the axial direction and a support member which slidably guides the reciprocating member. In a sealing device provided, an annular base portion holding the packing on a reciprocating member, an annular seal lip projecting outward to the outer peripheral side of the base portion and slidingly contacting a supporting member, and an end of the base portion. And a tubular build-up portion which is made of the same material and stands upright, and the outer diameter of the build-up portion is made smaller than the outer diameter of the seal lip to form an annular shape between the build-up portion and the support member. It is characterized in that a gap is formed.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment in which the present invention is embodied in a seal for a gas spring used in a back door of an automobile will be described below with reference to FIGS. 1 and 2.

This gas spring is obtained by replacing the packing 9 of the gas spring having the conventional structure shown in FIGS. 4 and 5 with the sealing device of the present invention, and the other structures are the same as those of the gas spring having the conventional structure described above. , The same reference numerals are given in the drawings, and the description thereof will be omitted.

As shown in FIG. 1, the packing 9A according to the present invention is a packing provided with an annular base portion 17 and an annular seal lip 18 having a mountain-shaped cross-section protruding inwardly on the inner peripheral side of the base portion 17. And the base 1 is attached to the inner end of the base 17.
The tubular build-up portion 19 is integrally erected with the same member as 7, and the inner diameter of the build-up portion 19 is made larger than the inner diameter of the seal lip 18.

Although this packing 9A can be used alone, as shown in the figure, the base portion 17, the seal lip 18, and the built-up portion 19 constitute an inner peripheral lip 15A, and the core metal 16 is provided at the base end of the base portion 17. Is provided, and the inner peripheral lip 15A is provided on the core metal 16.
And an outer peripheral lip 14 that faces in the radial direction may be provided.

FIG. 2 shows a sealing device for sealing the sliding gap between the bearing 7 and the piston rod 3 by using the packing 9A.

That is, this seal device has a sliding gap formed between the piston rod 3 which is a reciprocating member which reciprocates in the axial direction and the bearing 7 which is a supporting member which slidably guides the piston rod 3. A packing 9A for sealing is provided.

Then, the packing 9A is attached to the bearing 7
The annular base 17 held by the base 17, the seal lip 18 having a mountain cross-section protruding inward toward the inner peripheral side of the base 17 and slidably contacting the piston rod 3, and integrally erected at the end of the base 17 with the same material. And a tubular build-up portion 19
The inner diameter of the build-up portion 19 is made larger than the inner diameter of the seal lip 18 to form an annular gap L between the build-up portion 19 and the piston rod 3.

Explaining in more detail below, the sealing device of the present invention is such that the base portion 1 of the inner peripheral lip 15 shown in the conventional example.
A built-up portion 19 made of the same material as that of the base portion 17 is integrally formed on the inner end portion of the body 7 so as to stand upright.

The inner peripheral surface of the built-up portion 19 is a flat surface portion 20 which faces the piston rod 3 and is separated from the piston rod 3 by a predetermined distance, and the outer peripheral surface thereof has the same inclination as the outer peripheral surface of the base portion 17. It is formed by an inclined surface.

Therefore, the sealing device of the present invention has a shape in which the built-up portion 19 having a substantially trapezoidal cross section is added to the tip portion of the conventional seal lip, and the built-up portion 19 is extended. Thus, the maximum axial pressure gradient between the inner peripheral lip 15A and the piston rod 3 is reduced.

However, the maximum surface pressure gradient can be lowered even when the built-up portion 19 and the seal lip 18 are extended with the same diameter, but in this case, on the contrary, the inner circumference of the built-up portion 19 is the piston rod 3 There is a problem that the friction increases due to the sliding contact with the outer surface of the.

For this reason, an annular gap L is formed between the built-up portion 19 and the piston rod 3 to prevent the occurrence of friction and, at the same time, allow the gas pressure to enter.

Next, the operation of the present embodiment configured as described above will be described. First, in a normal back door opening / closing operation, the piston rod 3 repeats the retracting operation from the cylinder 1, and Between the seal lip 18 of the peripheral lip 15A and the outer peripheral surface of the piston rod 3, the lubricating oil O is constantly supplied by the enclosed gas pressure and an oil film having a predetermined thickness is formed.

At this time, in the conventional case, the internal pressure of the cylinder is increased by the enclosed high-pressure gas, so that the surface pressure itself is increased and the maximum surface pressure gradient in the axial direction is increased to thin the oil film. In the present embodiment, since the built-up portion 19 that exerts the effect of reducing the maximum surface pressure gradient in the axial direction is provided on the inner peripheral end portion of the base portion 17 of the inner peripheral lip 15A, the oil film does not become thin.

As shown in FIG. 2, this is because the inner peripheral lip 15A itself is pressed against the outer peripheral surface side of the piston rod 3 by the internal pressure, and in the extension stroke in which the oil film is formed, it is directed in the direction of arrow A in the figure. This is because a frictional force acts, and at this time, the deformation of the lip 18 is restrained due to the presence of the overlay portion 19, and a force in the outer peripheral direction indicated by an arrow B in the drawing is generated.

Therefore, when the axial surface pressure distribution between the inner peripheral lip 15A and the piston rod 3 is theoretically calculated by actually using the finite element method, as shown in FIG. In comparison with the maximum surface pressure gradient R of the inner peripheral lip without the built-up portion in the surface pressure distribution characteristic of, the maximum surface pressure gradient S of the inner peripheral lip 15A of the surface pressure distribution characteristic of the present embodiment shown by Q in the figure It is lower, which proves the effect of the present invention.

As described above, in the present embodiment, the base 1
Since the maximum surface pressure gradient can be reduced by the built-up portion 19 provided on the piston 7, even if the gas pressure in the cylinder 1 is high, the outer peripheral surface of the piston rod 3 and the inner peripheral lip 15
Not only can the oil film formed between A and A be made to have an appropriate thickness at all times, but there is no need to perform special processing on the tip of the seal lip as in the conventional case, so this sealing device itself can be manufactured at low cost. it can.

Further, since the built-up portion 19 is made of the same material as that of the base portion 17 and is integrally formed at the time of molding the packing 9A, the sealing device itself can be manufactured at a lower cost.

Further, in the present embodiment, the packing 9A is provided on the bearing 7 side, but the present invention is not limited to this, and naturally, the piston 2 as the reciprocating member and the cylinder 1 as the supporting member for guiding the piston 2 are provided. A packing 9A may be provided on the outer circumference of the piston 2 in order to seal the sliding gap between them.

However, in this case, since the seal lip 18 of the present invention is in sliding contact with the inner peripheral surface of the cylinder 1, the seal lip 18 is formed so as to project toward the outer peripheral direction of the base portion 17. It will be.

The present invention is not limited to the gas spring shown in the above-mentioned embodiment, but the present invention may be applied as a sealing device such as a hydraulic shock absorber or a hydraulic cylinder.

[0044]

The present invention has the following effects.

According to the invention of each claim, since the packing is provided with the built-up portion provided on the base portion, when this packing is used in the sealing device, the maximum axial surface between the packing and the reciprocating member is obtained. The pressure gradient can be lowered.

For this reason, not only can the oil film formed between the reciprocating member and the lip always have an appropriate thickness, but there is no need to perform special processing on the tip of the seal lip as in the conventional case. Therefore, the packing and the sealing device itself using the packing can be manufactured at low cost.

Similarly, since the built-up portion is made of the same material as the base portion and is integrally formed, the packing and the sealing device of the present invention can be manufactured at a lower cost.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part showing only a packing showing an embodiment of the present invention.

FIG. 2 is a fragmentary sectional view showing a state in which the packing shown in FIG. 1 is attached to a gas spring.

FIG. 3 is a graph showing a surface pressure distribution state of the sealing device of the present invention and the conventional sealing device.

FIG. 4 is a sectional view showing a conventional gas spring.

5 is a cross-sectional view of essential parts showing only the packing of the gas spring of FIG.

[Explanation of symbols]

3 Piston rod (reciprocating member) 7 Bearing (supporting member) 9A packing 15A inner lip 17 base 18 seal lip 19 Overlay part L annular gap

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Etsuro Nakata             2-4-1, Hamamatsucho, Minato-ku, Tokyo World Trade             Yasu Center Building Kayaba Industry Co., Ltd. F-term (reference) 3J006 AB02 AB11

Claims (5)

[Claims] 1. A packing having an annular base portion and an annular seal lip having a mountain-shaped cross-section protruding inwardly on the inner peripheral side of the base portion, wherein a tubular shape made of the same material is used at the end portion of the base portion. A packing characterized in that the built-up portion is integrally erected so that the inner diameter of the built-up portion is larger than the inner diameter of the seal lip. 2. A base portion, a seal lip, and a built-up portion constitute an inner peripheral lip, a core metal is provided at a base end of the base portion, and an outer peripheral lip radially opposed to the inner peripheral lip is provided on the core metal. The packing according to claim 1, wherein 3. A packing having an annular base portion and an annular seal lip having an outwardly projecting mountain-shaped cross-section on the outer peripheral side of the base portion, wherein the end portion of the base portion has a cylindrical meat made of the same material. A packing in which the raised portion is integrally erected and the outer diameter of the built-up portion is smaller than the outer diameter of the seal lip. 4. A sealing device comprising a packing for sealing a sliding gap formed between a reciprocating member and a supporting member for slidably guiding the reciprocating member in an axial direction. An annular base portion held on the member,
Consists of an annular seal lip having a mountain-shaped cross section that protrudes inward toward the inner peripheral side of the base and is in sliding contact with the reciprocating member, and a cylindrical build-up portion integrally erected at the end of the base with the same material. Then
Further, the sealing device is characterized in that an inner diameter of the overlay portion is larger than an inner diameter of the seal lip to form an annular gap between the overlay portion and the reciprocating member. 5. An apparatus comprising a packing that seals a sliding gap formed between a reciprocating member that reciprocates in the axial direction and a support member that slidably guides the reciprocating member. To a reciprocating member, an annular seal lip having a mountain-shaped cross section that protrudes outwardly on the outer peripheral side of the base and is in sliding contact with the supporting member, and stands up integrally at the end of the base with the same material. And an outer diameter of the overlay portion is smaller than an outer diameter of the seal lip to form an annular gap between the overlay portion and the support member. Sealing device.